Land mobile radio (LMR) refers to a class of wireless communications that is designed for terrestrial communications between users. LMR systems are commonly arranged to facilitate communications capability for users in vehicles (using mobile radio transceivers) or on foot (using portable radio transceivers). LMR radio systems often involve at least one dispatch or command center which communicates with mobile and/or portable users through an LMR network.
LMR radio systems are increasingly migrating toward digital radio communication system architectures that offer various advantages as compared to conventional analog systems. One example of a well-known digital radio system architecture is Project 25 (P25). This architecture was developed by the Association of Public Safety Communications Officials International (APCO), the National Association of State Telecommunications Directors (NASTD), certain Federal Agencies, and the National Communications System (NCS). The P25 standard is made available through the Telecommunications Industry Association (TIA). Another example of a digital radio system architecture for LMR is Terrestrial Trunked Radio (TETRA). The TETRA standard for digital radio communications was developed by the European Telecommunications Standardization Institute (ETSI).
Although an LMR network such as P25 has many advantages, these systems remain primarily a narrowband service for voice communications. They are not considered cost effective for multimedia applications such as video. However, it is known that a Long Term Evolution (LTE®) network (e.g., an LTE network operating in the 700 Mhz range) can be overlaid upon an LMR network to allow LMR network users to benefit from the speed and low latency for which such networks are well known. Such an approach can facilitate a unified infrastructure that combines the strengths of both types of networks. As is known, the LTE standard for high-speed wireless communication is based on the GSM/EDGE and UMTS/HSPA technologies.
To facilitate such combined networks, manufacturers of mobile radios have begun offering equipment that combine digital LMR (e.g., P25) and LTE capabilities in a single integrated portable or mobile radio unit. Such devices offer the capability of high-speed data with robust LMR voice operation in a common ruggedized package.